Arduino Micro Power Questions

I want to understand how the Arduino Micro is powered, so that I can better understand how to create my own circuit based off the Arduino Micro schematic.

I'm planning on building a project that will be powered strictly off USB. So does this mean I won't need the regulator and voltage selector modules of the Arduino Micro schematic (picture for reference below)?

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I assume that the +5V (and +3.3V line is generated from the voltage regulator module (if you have some power source connected to VIN). So if I'm powering off of USB (and don't have the voltage regulator) how will the +5V line be powered?

Also, do I still need all the other components (connected to the left side inputs/outputs) if I am powering off of USB?

If you are powering from USB only (which is 5V +/5 0.25V), you don't need a 5V regulator or the auto-switching circuit, just the 3.3V regulator.

CrossRoads: If you are powering from USB only (which is 5V +/5 0.25V), you don't need a 5V regulator or the auto-switching circuit, just the 3.3V regulator.

What I want to know is, how/what will power these +5V?:

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Those +5V would normally come off the 5 V regulator (correct?). So if I don't have a 5 V regulator, how will I hook up those parts of the circuit? Will I connect VUSB to +5V?

Also, I won't need a 3.3 V regulator if I don't plan on using 3.3 V, right?

Yes, power 5V from the 'output' of the USB polyfuse, F1, VUSB.

If you're not using 3.3V, you can leave off the 3.3V regulator.

CrossRoads: Yes, power 5V from the 'output' of the USB polyfuse, F1, VUSB.

If you're not using 3.3V, you can leave off the 3.3V regulator.

That makes much more sense. Thank you!

If you want simple, perhaps you would base your design on the DF Robot Beetle instead of the Micro. Same MCU but much less circuitry, just a resonator, few resistors and capacitors and an LED. You can connect as many pins as you want to header pins.